Surgical tools such as needles and cannulas are widely used in medical procedures. Several percutaneous needle-based procedures employ needles with a bevel or a symmetric tip for a specific procedure. In almost all instances, these needles need to be ‘steered’ to the target location by a variety of maneuvers at the distal end of the needle. Often, these needles need to be re-introduced or withdrawn slightly to correct for errors in targeting resulting from needle and soft tissue interaction. The problem is further compounded when there is a change in the tissue consistency as the needle traverses through the tissue or the tissue includes calcified regions, which can deflect the needle from its pre-planned trajectory. Some of the common examples where percutaneous needle-based procedures are employed are in prostate biopsy and breast biopsy (prostate cancer and breast cancer being the most prevalent cancers detected in men and women, respectively, in the US).
Trajectory corrections must be made during needle steering in order for the needle to reach its target. When flexible needles with a bevel tip are inserted into soft-tissue, they bend due to tip asymmetry. Taking advantage of this fact, steering of flexible needles can be accomplished by rotating the needle base during insertion to steer around obstacles. However, there is no local actuation along the length of the flexible needle, and this method of steering relies entirely on tissue reaction forces. The minimum radius of curvature is also limited, further limiting the steering capability.
Thus, there is a need in the pertinent art for medical probes (such as needles or cannulas) that overcome tissue reaction forces, achieve precise positioning, and exert force on soft-tissue to make appropriate trajectory corrections during insertion.